Abstract: A method for the calcination of powdery or fine-particled plaster, comprising two steps: the plaster is subjected to a flash-calcination in a calcinator and the hot plaster is post-calcinated in a reaction vessel. Post-calcination is carried out in the reaction vessel by adding humid gas, said reaction vessel not being heated. The postcalcination takes place over a long period of time, that is at least 10 times, preferably 50-100 times longer than the amount of time taken for flash calcination. Calcination takes place without expending additional energy, and the remaining dihydrate produced during the flash calcination is also transformed into semi-hydrate and undesired anhydrite fractions are reduced. The method can ensure consistency in the product quality and also increase product quality. The temperature in the upstream calcinator can be lowered thus saving more energy. The method can also be used to accelerate the ageing of calcinated plaster.

Abstract: A method for the calcination of powdery or fine-particled plaster, comprising two steps: the plaster is subjected to a flash-calcination in a calcinator and the hot plaster is post-calcinated in a reaction vessel. Post-calcination is carried out in the reaction vessel by adding humid gas, said reaction vessel not being heated. The postcalcination takes place over a long period of time, that is at least 10 times, preferably 50-100 times longer than the amount of time taken for flash calcination. Calcination takes place without expending additional energy, and the remaining dihydrate produced during the flash calcination is also transformed into semi-hydrate and undesired anhydrite fractions are reduced. The method can ensure consistency in the product quality and also increase product quality. The temperature in the upstream calcinator can be lowered thus saving more energy. The method can also be used to accelerate the ageing of calcinated plaster.

Abstract: A method for the production of hard plaster, a calcining plant, and a retrofit reactor for calcining plants. The method includes feeding plaster material, predominantly including beta-hemihydrate plaster, to a postreactor. The temperature is set to at least a calcining temperature of 95° C. during this step. The plaster material is retreated in the postreactor to form hard plaster, the beta-hemihydrate plaster being converted directly into alpha-hemihydrate plaster at a temperature above 95° C. The hard plaster can then be discharged out of the postreactor and cooled. Conversion can be carried out in the postreactor during continuous operation, and conversion of the beta-hemihydrate plaster can occur with a dwell time in the postreactor of less than 30 minutes. Steam can be externally supplied to the postreactor and the temperature and pressure in the postreactor can be regulated so that the temperature is at least 95° C. and an over pressure prevails.

Abstract: A solids distributor for injection plants includes a collecting chamber having a plurality of lance lines leading away from the chamber. The chamber has a supply connection for a solid to be distributed and is surrounded by a common wall in which a plurality of ports is formed. The lance lines are connected to the ports, and an annular gap is formed in front of the ports and along the common wall. A pressure vessel is arranged geodetically above the collecting chamber, the lower part of the pressure vessel being designed as a bunker, having an outlet providing a direct and continuous junction to the supply connection and an upper part designed as a gas space. The collecting chamber may include a central displacement body which forms the annular gap with the common wall and which may be an upwardly tapering cone which projects out of the collecting chamber.

Abstract: The invention relates to a method for the production of hard plaster made from calcined beta hemihydrate plaster, comprising adding of plaster material mainly consisting of beta hemihydrate plaster to a post reactor (3), after-treating in the post reactor (3) for forming hard plaster, wherein the beta hemihydrate plaster is directly converted into alpha hemihydrate plaster at a temperature above the calcining temperature of 95 degrees Celsius, removing the hard plaster from the post reactor (3), and cooling down. During the adding of the plaster material to the post reactor (3) the temperature is adjusted to at least the calcining temperature, the conversion is carried out in the post reactor (3) at a dwell time of less than 30 minutes while externally adding water vapor, and the temperature and the pressure in the post reactor (3) are regulated such that the temperature is at least 95 degrees Celsius and an overpressure is present.

Abstract: A drying mill for powdered or fine-grained material, in particular also suitable for calcining gypsum, employs a housing, in which a feed device for fuel gas, opening into a lower region, a comminuting device and a material inlet, charging the material onto the comminuting device from above, are provided one above the other, a material outlet leading to the outside from an upper region of a working chamber and a return leading downwards to the comminuting device, the comminuting device being a centrifugal disc which rotates in a horizontal plane and interacts with an impact casing arranged on the inside of the housing. A nozzle ring surrounding the centrifugal disc from below is provided for feeding fuel gas into the working chamber. As a result, the calcining process in particular is assisted in an efficient way by utilizing the thermal energy of the hot gas fed into the working chamber by means of the nozzle ring and the dwell time in the working chamber. A corresponding comminuting method is provided.

Abstract: A method for the calcination of powdery or fine-particled plaster includes steps in which the plaster is subjected to a flash-calcination in a calcinator and then post-calcinated in a reaction vessel. The post-calcination is carried out in the reaction vessel by adding humid gas, the reaction vessel not being heated. This post-calcination takes place over a long period of time, that is at least 10 times, preferably 50-100 times longer than, the amount of time taken for flash calcination. Complete calcination can take place without expending additional energy, and the remaining dihydrate produced during the flash calcination is also transformed into semi-hydrate and undesired anhydrite fractions are reduced. The method ensures consistency in the product quality and also increases product quality. The temperature in the upstream calcinator can be lowered to save energy. The method can also be used to accelerate the ageing of calcined plaster.

Abstract: A solids distributor for injection plants includes a collecting chamber having a plurality of lance lines leading away from the chamber. The chamber has a supply connection for a solid to be distributed and is surrounded by a common wall in which a plurality of ports is formed. The lance lines are connected to the ports, and an annular gap is formed in front of the ports and along the common wall. A pressure vessel is arranged geodetically above the collecting chamber, the lower part of the pressure vessel being designed as a bunker, having an outlet providing a direct and continuous junction to the supply connection and an upper part designed as a gas space. The collecting chamber may include a central displacement body which forms the annular gap with the common wall and which may be an upwardly tapering cone which projects out of the collecting chamber.